Lawinenlagebericht

Summit Lake

Chugach National Forest Avalanche Center
Auf der Karte ansehen

Lawinengefahr

Thu
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
Open full map
Veraltet — dieser Lagebericht ist 9 months ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

There's a chance a person could trigger a large avalanche 2' deep on a layer of weak snow above 2,000', which is the main concern in Summit Lake. Easterly winds are forecast to increase today on the ridgetops building fresh pillows of snow 1' deep or more that could be triggered by a person. Safer conditions can be found in areas protected from the wind and on lower angle slopes. Glide avalanches are releasing almost daily across forecast zones, avoid traveling underneath glide cracks because these avalanches are unpredictable and destructive.

__________________________________

SPECIAL ANNOUNCEMENTS: Turnagain Pass is opening to motorized use TODAY! Click here for Chugach National Forest riding area status.

Thank you for all of the great observations that have been submitted, keep them coming!

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    2

    Recent Avalanches: There have been two remotely-triggered avalanches on the south side of Tenderfoot last weekend. One occurred on Saturday, which was triggered by a skier ascending the ridge. The other was triggered on Sunday by people riding an adjacent lower angle slope. Another recent avalanche released during the storm last week at about 4,600' on a west slope of Hale-Bop. Several new glides were noticed on Tri-Tip, Fresno, Frenchy, and Butch.  

    There are several layers of surface hoar buried in the snowpack across zones and this type of weak layer is tricky and more difficult to assess.

    What we know: The remotely-triggered avalanches mentioned above mean this layer was very sensitive just 3 days ago. People are finding the weak snow on east and south aspects between 2,000' and 4,400' ususally about 1 to 1.5' below the surface right now. So far all test results on these layers in Summit have been unstable. Surface hoar can be an untrustworthy layer and if triggered, an avalanche would be large enough to bury a person so the consequences could be terrible.

    What we don't know: We don't have information from north and west aspects since this layers got buried. The most recent observations have been from Fresno and Tenderfoot so we don't know if these layers are as reactive on other mountains in the area. With the tricky nature of this weak layer it may not give warning signs and we don't know exactly where the trigger spots are located (usually thinner spots in the snowpack near rocks).

    What can we do about it: We can completely avoid this problem by sticking to slopes below 30 degrees with nothing steeper above. If steeper terrain is in the plan, a terrain progression including starting with smaller slopes with lower slope angles is a good way to approach a suspect snowpack. With the depth of these layers a snow pit is going to be the best assessment tool, but the snowpack is highly variable so a stable result in one area doesn't mean the next slope in either direction is good to go (or even the slope with the stable result). Safe travel protocols will help if we get surprised, which include one rider on steep slopes at a time, choosing good safe spots, and watching our partners closely. Ensure the group does a good safety check of all equipment (transceiver, airbag, radios, satellite communications) before leaving the parking lot.

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    Easterly winds are just starting to pick up this morning in the Summit Lake area. The forecast speed is 20 to 30 mph today, which isn't terribly strong, but should build some wind slabs on the softer side. Watch for blowing snow to avoid places where it is piling up into a slab. The bigger concern with a wind slab today is that if one is triggered by a person it could step down to a deeper weak layer (surface hoar described in problem 1) and create a bigger and more dangerous avalanche. Other signs we may have found a wind slab include firm snow over soft snow and a crack that shoots out from you (different than just some minor cracking around your feet).

  • Glide Cracks

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    2–3

    Unfortunately, the glide cycle is not showing signs of slowing. We've noticed more than 10 new glide avalanches since the last storm ended last Friday. The most recent on Repeat Offender in Turnagain Pass did not have an obvious crack before it released, which is the scary thing about this problem. The avalanches are very large, they are unpredictable, and sometimes not even the classic sign of a brown frown is present. Hopefully this cycle will come to an end or at least slow. Until then, route plan to avoid them completely and if that isn't possible, spend as little time as you can passing underneath. 

    Large glide that released sometime after the storm that ended last Friday on Butch Mountain

    Photo: John Sykes

Abgedeckte Regionen